The preparation of high resiliency polyurethane foams characterized by high strength and load bearing properties by the reaction of an organic polyisocyanate with a polyol in the presence of a crosslinking agent is well known in the art. Commercial polyurethane foam molders are always trying to optimize their formulations in a cost effective fashion so as to obtain the maximum set of properties from a given set of materials and processing conditions. It is desired to improve the physical properties at equivalent density or maintain physical properties at reduced density.
Shrinkage occurs in a molded article when the trapped hot gas within unopened cells cools and causes the cells to contract. Currently, methods have been developed (foam crushing) to open the closed cells upon demolding of the article. Generally, the use of crosslinker molecules increases the closed cell content of a molded polyurethane article relative to a control formulation.
The use of aromatic diamine crosslinkers has been suggested to provide benefit in molded polyurethane foams. However, such materials have demonstrated only marginal physical property improvements when compared to control formulations. In addition, aromatic diamines and their derivatives have controversial toxicological properties and thus require special handling.
Previously, increased water levels have been used to reduce foam density and maintain physical properties. The currently used water levels cannot, however, be increased further because of processing limitations.
U.S. Pat. No. 4,210,728 discloses a reactive polyol composition useful in the preparation of high resilient polyurethane foams comprising a polyol and from 0.5 to 5.0 wt % of a reactive cycloaliphatic diamine.
U.S. Pat. No. 4,248,756 discloses thermosetting two-component coating compositions containing a prepolymer having ketoxime-blocked aromatic isocyanate groups and, as a crosslinking agent, certain diamino dicyclohexyl methanes.
U.S. Pat. No. 4,108,842 discloses a process for the production of polyurethane ureas from a prepolymer and a mixture of hardeners containing amino groups.
U.S. Pat. No. 3,849,360 discloses polyurea-urethanes made by reaction of an isocyanate-terminated polyurethane prepolymer with a diamine component containing 4,4'-bis(aminocyclohexyl)methane and one or more diamines having a single alicyclic ring.
U.S. Pat. No. 4,293,687 discloses biscyclohexylamine derivatives.